Multi-wavelength fiber ring laser based on the semiconductor optical amplifier(SOA)with sampled fiber Bragg grating(SFBG)in a Sagnac loop interferometer as the wavelength-selective filter is proposed.Four lasing wavel...Multi-wavelength fiber ring laser based on the semiconductor optical amplifier(SOA)with sampled fiber Bragg grating(SFBG)in a Sagnac loop interferometer as the wavelength-selective filter is proposed.Four lasing wavelengths with 1.8 nm spacing have been generated stably at room temperature.The proposed laser has the advan-tages such as removal of the high-cost circulator,flexibility in channel-spacing tuning,and simple all-optical fiber configuration,which has potential applications in high-capacity wavelength-division-multiplexed(WDM)systems and mechanical sensors.展开更多
A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber(PMF)between two sections of standard single mode fibers(SMFs).In...A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber(PMF)between two sections of standard single mode fibers(SMFs).In this sensor,the SMF-PMF-SMF structure in the Sagnac loop is bent into a circle to enhance the sensitivity.The length and curvature of the PMF in the loop are investigated and can be optimized to further increase the temperature sensitivity of the sensor. Results show that the radius of the circle has an important effect upon temperature sensitivity due to the bend-induced birefringence variation of the PMF.The SMF-PMF-SMF structure bent into a circle with a radius of 30mm exhibits a high-sensitivity temperature of 1.73nm/℃.The sensor is provided with the advantages of easy fabrication,low-insertion loss,and high sensitivity,which may find potential applications in the field of high precision temperature measurement.展开更多
A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be use...A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics.展开更多
Weigh-in-Motion（WIM） technique is the process of measuring the dynamic tire forces of a moving vehicle and estimating the corresponding tire loads of the static vehicle. Compared with the static weigh station, WIM s...Weigh-in-Motion（WIM） technique is the process of measuring the dynamic tire forces of a moving vehicle and estimating the corresponding tire loads of the static vehicle. Compared with the static weigh station, WIM station is an efficient and cost effective choice that will minimize unneccessary stops and delay for truckers. The way to turn birefringence of single-mode fiber into a prime quality for a powerful and reliable sensor is shown. Preliminary results for the development of a weigh-in-motion （WIM） technique based on sagnac-loop sensor are presented. After a brief description of the sensor and its principle of operation, the theoretical model characterization made in is developed. Then, a full static conditions is presented.展开更多
基金supported by the National“863” Project of China(2007AA01Z258)the National Natural Science Foundation of China(60771008)+2 种基金Program for New Century Excellent Talents in University(NCET-06-0076)Beijing Natural Science Foundation(4082024)the Beijing Jiaotong University Foundation(2006XM003)
文摘Multi-wavelength fiber ring laser based on the semiconductor optical amplifier(SOA)with sampled fiber Bragg grating(SFBG)in a Sagnac loop interferometer as the wavelength-selective filter is proposed.Four lasing wavelengths with 1.8 nm spacing have been generated stably at room temperature.The proposed laser has the advan-tages such as removal of the high-cost circulator,flexibility in channel-spacing tuning,and simple all-optical fiber configuration,which has potential applications in high-capacity wavelength-division-multiplexed(WDM)systems and mechanical sensors.
基金the National Natural Science Foundation of China(NSFC)(Grant Nos.61425007 and 61635007)Guangdong Natural Science Foundation(Grant Nos.2015B010105007 and 2014A030308007)+3 种基金Science and Technology Innovation Commission of Shenzhen(Grant Nos.JCYJ20170412105604705 and JCYJ20160427104925452)Development and Reform Commission of Shenzhen Municipality Foundationthe National Natural Science Foundation of China(Grant No.61565002)Guangxi Province Key Research and Development Program(Grant No.AB171129027).
文摘A high-sensitivity all-fiber temperature sensor based on a Sagnac interferometer is demonstrated by splicing a section of polarization maintaining fiber(PMF)between two sections of standard single mode fibers(SMFs).In this sensor,the SMF-PMF-SMF structure in the Sagnac loop is bent into a circle to enhance the sensitivity.The length and curvature of the PMF in the loop are investigated and can be optimized to further increase the temperature sensitivity of the sensor. Results show that the radius of the circle has an important effect upon temperature sensitivity due to the bend-induced birefringence variation of the PMF.The SMF-PMF-SMF structure bent into a circle with a radius of 30mm exhibits a high-sensitivity temperature of 1.73nm/℃.The sensor is provided with the advantages of easy fabrication,low-insertion loss,and high sensitivity,which may find potential applications in the field of high precision temperature measurement.
基金the Fundamental Research Foundation of Harbin Engineering University, (grant number HEUF 04017)
文摘A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics.
基金supported by the National Natural Science Foundation of China under Grant No. 60707021Science and Technology Commission of Shanghai Municipality under Grant No. 03dz11003.
文摘Weigh-in-Motion（WIM） technique is the process of measuring the dynamic tire forces of a moving vehicle and estimating the corresponding tire loads of the static vehicle. Compared with the static weigh station, WIM station is an efficient and cost effective choice that will minimize unneccessary stops and delay for truckers. The way to turn birefringence of single-mode fiber into a prime quality for a powerful and reliable sensor is shown. Preliminary results for the development of a weigh-in-motion （WIM） technique based on sagnac-loop sensor are presented. After a brief description of the sensor and its principle of operation, the theoretical model characterization made in is developed. Then, a full static conditions is presented.
